A flow cell system has been designed and fabricated at SSRL for use in Laue diffraction experiments which require flowing reactant substrates over an enzymatic protein crystal. Solutions are introduced to the cell via syringes that are automatically driven at a user selectable speed with a stepper syringe driver. Connections of tubes containing mother liquor and substrate solutions to the flow cell are selected using a electronic micro-solenoid. This allows simple and bubble-free switching of solutions. The system has been used successfully for Laue diffraction experiments.